Part 1. Definition
In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.
Part 2. Example
In early work , Rutherford discovered the concept of radioactive half-life, the radioactive element radon, and classified three types of radiations: alpha, beta and gamma radiation .

Answer: Rutherford discovered the radioactive half-life, the chemical element radon, and the three parts of radiation which he named Alpha, Beta, and Gamma .

Explanation: The output sentence is a simplified version of the input sentence.
Part 3. Exercise
The kilogram ( also kilogramme ) is the base unit of mass in the metric system , formally the International System of Units ( SI ) , having the unit symbol kg .
Answer:
The kilogram is the base unit of mass in the International System of Units ( SI ) .